If I can push it a little more... since he is licensed to carry in both states, do you see any problem with him bringing one of his pistols back to MA when he comes to his home in MA, and lending it to me in person?
ETA: At the time of "transfer" he would be an MA resident (staying at his MA apartment) so my thought is it would no longer be across state lines? At least from what I've been able to read on the ATF website, it seems the ATF considers dual state residents to be a resident of whatever state they are currently in provided they legitimately hold a residence in that state.